Linking arson incidents on the basis of crime scene behavior

The present study investigated the possibility of statistically linking arson cases based on consistency of behaviors from one crime scente to another. Serial and spree arson cases were studied to differentiate underlying themes and to link cases committed by the same offender. The material consisted of 248 arson cases which formed 42 series of arsons. A content analysis using 45 dichotomous variables was carried out and principal compnents (PCA) analysis was performed to identify underlying themes. Summary scores reflecting the themes were calculated. Linking effectiveness was tested with a discriminant analysis using the summary scores. The PCA analysis was successful and underlying themes which were in accordance with previous studies could be identified. Six factors were retained, in the PCA. The linking of the arson cases was possible to a satisfactory level: 33% of the cases could be correctly linked and for over 50% of the cases, the series they actually belonged to was among the ten series identified as most probable on the basis of the linking analysis. From a practical point of view, the results could be used as a basis for developing support systems for police investigations of arson. This research was financially supported by the Finnish Ministry of Interior and by Grant 54456 from the Academy of Finland.